Resurfacing machine for propeller shafts



July 21, 1964 K. R. KELLEY ETAL.

RESURFACING MACHINE FOR PROPELLER SHAFTS Filed June 15, 1960 Wei/NE Poo/w OUTER STEM; 7175s 4 Sheets-Sheet 1 K. R. KELLEY ETAL 4 Sheets-Sheet 2 July 2l, 1964 RESURFACING MACHINE FOR PROPELLER SHAFTS Filed June 15, 1960 July 21, 1964 K. R. KELLEY Em. 3,141,364

RESURFACING MACHINE FOR PROPELLEZR SHAFTS Filed June 15, 1960 4 Sheets-Sheet 3 @www Arran/fm July 21, 1964 K. R. KELLEY r-:TAL 3,141,364

RESURFACING MACHINE FOR PROPELLER SHAFTS Filed June 15, 1960 4 Shees--Sheetl 4 THEL.

A TTOANE United States Patent O 3,141,364 RESURFAClNG MACHINE FR PRIELLER SHAFT The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates in general to resurfacing machines for circular or cylindrical machining, and more particularly to resurfacing and machining of shafts without removal of the shaft from its operative position.

In the past, resurfacing or machining of shafts has necessitated the removal of the shaft to a shop equipped for carrying out this operation particularly where large diameter shafts are involved. This is particularly true where precision machining is desired since in-place operations have always been subject to vibration, eccentricity of the turned shaft, space problems, poor mounting facilities, large machines and danger to operating personnel. This problem has existed for many years and various solutions have been suggested and tried without satisfactory results. This long-standing problem has recently become more acute in many fields, as, for example, aboard ships where higher speeds have become possible with more ecient engines and power plants. The result of these improvements has caused main propeller shafts to become worn and disable vessels having only one shaft such as submarines, or reduce the speed of Vessels equipped with multiple shafts. Under either condition, the ship must be drydocked and the shaft repaired as soon as possible, thereby deactivating the ship for a considerable length of time.

One frequent and common repair of the shaft will illustrate the procedure and problems which are encountered and solved by this invention. The main ship propeller shaft, which couples the drive mechanism to the propeller passes through the stern hull section of the ship and therefore requires a watertight bearing at this or a proximate location, Generally, this stern tube bearing is located well within the contines of the ship since that portion of the shaft and its appurtenant bearings are lubricated by sea water. This inner stern tube bearing consists in part of a stuffing tube box which encloses and confines a packing material between the inner surface of the box and a metallic sleeve or journal which abuts the outer surface of the propeller shaft although allowing free rotation of the shaft. Due in part to normal wear and the fact that foreign matter entering via sea water becomes deposited and embedded within the packing material, the sleeve becomes damaged and scored so that either the system develops a leak or the packing material binds the shaft through the sleeve. When this condition arises, the sleeve must be resurfaced and the packing replaced. The present procedure generally followed consists of removing that portion of the propeller shaft carrying the sleeve while the ship is in drydock, resurfacing the sleeve and then reassembling the propeller shaft. This procedure at first impression may appear to be quite simple, but this is not the case when one considers that for most ships the diameter of the shaft exceeds one foot and the propeller and its auxiliaries must also be removed. The remaining portions of the shaft must be independently supported, the shaft which is located in the lowermost section of the ship must be removed with the ldlhd Patented July 21, 1964 ICC use of cranes. At best, the entire operation is costly and time consuming, as for example, for ships having an 18 inch shaft, the cost ofresurfacing may exceed $12,000 and the time required may be as high as l0 working days in addition to the expense of drydocking.

An object of this invention is to provide an apparatus for resurfacing or machining in place, shafts and the like.

Another object is to provide a simple, efficient, inexpensive and accurate device for resurfacing or machining shafts Without removing the shafts from their operative position.

A further object is to provide a method for precision resurfacing or machining of shafts while in their operative position.

A still further object is to provide a simple, practical, inexpensive method for precision resurfacing or machining of shafts aboard ships while the shaft is in operative position without drydocking the ship.

Still another object of this invention is to provide a simple, practical, inexpensive device for precision resurfacing or machining of shafts and shaft sleeves aboard a ship without removing the shaft or sleeve from its operative position and without the necessity of drydocking the ship.

Other objects and advantages will be apparent from the following description of an embodiment of the invention and the novel features thereof Will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

FIG. l is a front elevation of the stern portion of the main ship propeller shaft;

FIG. 2 is a perspective drawing illustrating the embodiment made in accordance with this invention mounted on a shaft over the sleeve to be machined;

FIG. 3 is a perspective drawing illustrating a partly disassembled portion of the embodiment of FIG. 1;

FIG. 4 is a perspective drawing of a portion of the embodiment of FIG. l, and

FIG. 5 is a cross-sectional plan approximately along 5-5 of FIG. 4.

The embodiment made in accordance with this invention illustrated herein has been shown as mounted on a ships main propeller shaft whose journal or sleeve is to be resurfaced. The sleeve or journal serves to prevent sea Water from entering the ship and a typical arrangement of the stern shaft section is shown in FIG. l. The propeller shaft 1 extends from the ships reduction assembly (not shown) via several couplings to the inner stern tube 2, then through the outer stern tube 3 to the propeller 4. Both the inner and outer stern tubes contain bearings which are lubricated by sea water. Mounted concentric with the sleeve or journal 5 is a stuffing tube or box 6 which is attached to the forward end of the inner stern tube. Packing material (not shown) is disposed between the journal 5 and the inner surface of the stung box, thereby maintaining the watertight integrity of the system. The journal is usually made of brass, bronze or similar suitable metal and is sweated on over the propeller shaft. The journal after a period of time becomes scored by the abrasive action of the packing material and by the sand and grit deposited thereon by the salt water within the inner stern tube and the sleeve must be resurfaced in order to maintain a watertight seal. During this operation the packing is also replaced. In order to resurface the journal by prior methods, the section of the shaft carrying the journal had to be removed and the machining accomplished at another location such as a machine shop. Removal of the shaft aft of the coupling is required and this therefore includes disassembly and removal of the propeller, palms, strut and hanger which operation is both expensive, time consuming and diilicult where large shafts are involved.

In the embodiment of the invention illustrated in FIGS. 2`through 4, the resurfacing machine comprises an encircling assembly 7 which carries a tool holder 8 and is mounted on the shaft lrfor rotation about the surface to be machined.

A motor 9 for driving the encircling assembly is mounted and supported adjacent the encircling assembly by a pair of right semicircular metallic cylinders 10 and 11 whose inner surfaces tightly abut and conne the cylinders on the shaft against movement thereon.

These encircling complementary cylinders are each provided with a pair of lateral coupling flanges 12 and 13 that may be joined together by bolts 14 passing through aligned holes in the flanges, whereby the cylinders may be individually placed on the shaft and then coupled together. One of the cylinders 10 carries a radial outwardly extending support 15 which is secured to that cylinder section by welding or other suitable means such as rivets. Mounted securely on the free end of the extending support is an air motor 9 or any other suitable driving device, as for example, an electric motor, although an air motor is preferable where accurate speed control is necessary. The motor is provided with a circular gear 16 whose axis of rotation is parallel to and spaced from the shaft, which is driven by the motor and meshed or coupled to a bull gear 17 which forms a part of the encircling assembly 7.

The encircling assembly which is also illustrated in FIG. 3 comprises a main member which is made up of two elongated hemispheric cylinders 13 that may be joined together to form a right circular cylinder. Each cylinder of the main member has a pair of outwardly extending llanges 19 at one end, which serves asa bearing and 20 at the other end which is allixed to the circular bull gear 17 by bolts. The gear teeth of the bull gear are located along its outer radial peripheral edge. The two cylinder portions 18 are joined together by bolts 21 which pass through abutting flange extensions 22 and 23 to form the main assembly. Apertures 24 are provided through the flange portion of the bull gear in a direction along the shaft axis so as to reduce the weight of the machine. The flange of the bull gear 17 is provided with an opening 25 as illustrated in FIG. 4 and an internal bearing (not shown) within housing 26 through which feed screw 27 passes. Aligned with the aperture 2S and attached to the cylinder 18 near but spaced from the opposite flange or flange bearing 19 is a lock plate 2S also provided with an internal bearing, so that the feed screw may be rotated by a star wheel 29 disposed at the other end of the feed screw. Surrounding the screw 27 along its length is a cylindrical boring bar assembly cover 30 which is ailixed to the lock plate at one end and attached to the bull gear flange at the other end where it passes therethrough. The assembly boring bar cover is provided with a longitudinally extending slot 31 so that the machine tool holder S may contact the feed screw and ride along the assembly cover in a direction lengthwise of the shaft while being supported thereon. The tool holder 8 illustrated in FIG. 5 is provided with a lengthwise passage 3?.. which is, for the most part, circular in cross-section, and thereby may slidingly abut the outer surface of the boring bar cover 30. That portion of the passage 32 which faces the longitudinal slot 31 of the boring bar cover is provided with a recess 33 or lengthwise slot having at least two abutments and a feed-screw nut 34 whose outer walls abut the recess walls is disposed within the recess so that the nut may not turn or rotate with rotation of the feed-screw. The semi-circular recess 35 lengthwise of the nut is internally threaded to mate with the feed-screw 27. The feed nut is held in place and against the feed-screw by a set or retaining screw 36 which passes radially through the tool holder and bears against an outer face of the feed nut which may be countersunk to accept the screw. This serves to hold the tool holder and nut in their operating relation. When the screw 36 is loosened the holder may be slid lengthwise and disengaged from the nut and rotated independently. In operating position, as the feed-screw is turned by the star wheel, the tool holder will progress toward or away from the star wheel depending on the direction of rotation. Since the holder cannot rotate and the feed nut is held in position, although the above method has been found satisfactory, it should be noted that many standard techniques are available for progressively moving the tool holder in a lengthwise direction. The tool holder is provided with standard recesses 37 having keyed passages for retaining the bits 38 or abrasion tools used for machining. The tools are securely held therein by locking and adjusting screws 39. The tools may be easily removed or adjusted by these screws 39. The diameter of the tool holder and the position of the boring bar assembly are such that the tool may be adjusted to contact the surface to be machined and adjusted for any required depth of cut. The encircling cylinders 18 of the encircling assembly have a lengthwise cut-out 4i) extending almost from the base of the bull gear to the bearing flange 19. This cut out allows the tool to contact the surface to be machined along a length suilicient to machine a useable portion of the journal and of a suicient height to permit Visual observation of the machined surface.

The bearing llange 19, as illustrated in FIGS. 2 and 3, is integral with the encircling assembly (cylinders) and extends radially therefrom. It is disposed between a back plate 41 and a keeper ring assembly 42 so as to permit the encircling assembly to rotate and also provide a thrust bearing for the bull gear and the assembly. The back plate 41 which comprises two split or half rings abuts the peripheral edge of the inner stern tube. It is approximately L-shaped in cross-section so that the leg portion 43 serves as -a spacer between the longer arm 44 and the keeper ring 42 and since the width of the spacer portion 43 is approximately equal to the thickness of the flange 19 which rides and rotates therebetween, it is in effect a thrust bearing. The radius of the bearing llange 19 is just slightly smaller than the radial length measured from the center of the shaft to the inner peripheral wall of the spacer portion i3 of the back plate so that the flange Abearing and the encircling assembly are thereby partially supported Labout the shaft. The keeper ring and the back plate are each fabricated in sections, as for example, two semicircular rings whereby they may be placed around the shaft and bolted in position to the edge of the inner stern tube.

With the entire assembly thus supported, only by the thrust bearing, it is possible to rotate vthe assembly about the shaft and machine the journal 5 which is disposed under or within the encircling assembly. This rotational arrangement, however, would not result in the machining precision necessary and would be somewhat eccentric. Semicircular filler rings 45 are fastened to the inside surface of the end portions of the encircling assembly by countersunk screws. They are disposed `at the end portions lof the assembly near the flange and bull gear and are of a width so as to approximately underlay that portion of the encircling assembly over which the cut-out 4@ does not extend. The filler rings ride on that portion of the journal or sleeve that is not to be machined (not damaged) and are to serve as bearing supports for the rot-ation of the encircling assembly. The thickness of the filler rings is selected so that the rings (i.e. diameter of the ring) or their inner surfaces properly abut the outer surface of the journal 'and thereby insures a smooth running `fit. The thickness of these rings is also selected so that the method and the device of this invention may be employed on different sized shafts. The tiiller rings are provided with an extremely smooth inner surface in order to permit ease of rotation and high efficiency and precision. Substitution of roller bearings for the lller rings will increase the precision of machining from 1 or 2 mils to far less than a fraction of l mil.

Although the method and apparatus of the invention may be employed for various in-place machining, the following explanation relative to the main propeller shaft of a ship will serve as a satisfactory illustration. FIG. 1 indicates the relative relationship and positions of the various components making up the stern section of the propeller drive coupling. kThe inner and outer stern tubes are lubricated by sea water and in order to prevent this water from entering the ship, a stuffing box 6 is employed at the end of the inner stern tube. The stuing box consists in part of an outer tube, a bronze sleeve 5 which has been, as is common, sweated on to the shaft 1. The sleeve is concentrically aligned with the outer tube with packing material between the tube and sleeve, thereby forming a watertight bearing. As is generally the case after some use, the central portion of the sleeve becomes damaged and must be resurfaced to prevent excessive entry of water into the ship. Prior methods of resurfacing the sleeve required removal of the shaft which was both costly and time consuming. However, use of the device previously described as an embodiment of this invention obviates this removal.

The stern tube packing box and packing material are removed while the ship is in drydock and the shaft centered ywithin the inner stern tube by means of hydraulic jacks and inserts between the inner wall of the stern tube and the outer surface of the shaft. It should be noted at this point that only a central portion of the sleeve becomes damaged and it is only this portion that is to be machined, thereby permitting the filler rings 45 to bear against the end portions of the sleeve where the sleeve is quite concentric since it was machined accurately during fabrication. This is not always necessary where the shaft to be machined is relatively smooth and circular.

The device, as illustrated, has in effect complementary upper and lower assemblies which, in assembling, are rst individually assembled and then the lower assembly is mounted on the sleeve so that the filler rings ride on the outer undamaged portions of the sleeve. The upper assembly is then placed over the sleeve and attached to the lower assembly. The thrust bearing assembly is now bolted to the edge of the stern tube and the same threaded holes employed to aix the stuing box can be used, provided the holes in the .thrust bearing unit are aligned therewith. Horse shoe shims may be employed in attaching the thrust bearing back plate where there is excessive distortion of the inner stern tube. The air motor is mounted with its gear coupled to the bull gear and then the cylinder mountings tightened about the shaft.

The resurfacing machine is now ready to operate with the insertion of the desired tool into the tool holder. The tool holder is positioned at one end of its travel by means of the star wheel. It has been found satisfactory to operate the assembly at a rotational speed of 18 r.p.m. since this is fast enough for most purposes and yet safe for precision operation. Although an electric motor can be substituted for the air motor, the air motor is used abroad ships for several reasons, namely, a supply of air pressure is readily available, and a better speed control can be achieved at a lower cost with fewer components. The air motor by way of coupled gears 16 and 17 rotates the encircling assembly and the tool holder is progressively moved along at a selected rate by rotation of the star wheel which in turn rotates the feed screw, thereby moving the tool holder and so machining the sleeve over any selected exposed surface. The star wheel may, if desired, be rotated automatically by placing one or more stationary trips (not shown) in its path of travel. These trips may be secured to the shaft which is stationary by a shaft bracket and their number would determine the number of revolutions of the feed-screw per revolution of the encircling assembly or in effect the cross-feed rate. The entire boring bar assembly, including the star wheel, may be of any standard or well-known design and may include other features as are commonly employed by machinists.

After the sleeve has been machined to its proper dimensions, the packing material and box are replaced. Although this machining operation was described as being performed with the ship in drydock, the same procedure may be followed without the necessity and expense of drydocking if the outer stern tube is made watertight, as for example, by a diver sealing the outer stern tube, which procedure is a standard operation. This type of system is possible in View of the fact that the main propeller shaft remains stationary and does not rotate during the resurfacing, and therefore, the sealing does not require any type of watertight bearing. The entire resurfacing procedure as described is even more readily adaptable to recently built ships since some of these are provided with an inflatable tube located within the stern tube, whereby this tube may be inflated and the system made watertight. A possible extension of this technique may be made on vessels where the cargo can be shifted and made to act as a ballast, as for example, a tanker. In this way, the aft section of the ship may be raised out of the water and the machining completed with the ship in this position, out at sea.

The illustrated embodiment of this invention, as can readily be observed, is adapted to a variety of situations and types of machining operations where precision resurfacing of shafts or the like is required. Further, since the cross-feed and rotational speeds are variable, different cutting tools and grinding devices are possible and the space necessary to conduct the resurfacing is held to a minimum. In addition, the entire operation may be carried out manually simply by replacing the motive means or the motor by a gear train which may be suitably rotated manually and proportioned to turn the assembly since only a slow speed is required and the assembly is provided with rotational bearings.

It will be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

We claim:

1. An apparatus for resurfacing a peripherally extending area of a main propeller shaft of a ship from within the ship while the shaft is in operative position and idle, which comprises a speed controllable air motor having a rotatable driving element, complementary supports adapted to be connected together about said shaft for supporting said motor in a condition stationary with respect to said shaft, means for encircling said shaft adjacent said area to be resurfaced and rotatable about the axis of said shaft ring bearing means disposed between said encircling means and said shaft and in contact therewith, a drive coupling between said element and said encircling means, a machining ltool carried by and rotatable bodily with said encircling means and operable toward and from said area of said shaft to engage and machine said area as the tool rotates, means carried by said encircling means for feeding said tool progressively in a direction parallel to the shaft axis during its rotation with said encircling means and along said area, and means engaging said encircling means to take the thrust of said tool in a direction parallel to the axis of said shaft.

2. An apparatus for resurfacing a peripherally extending area of a shaft while the shaft is stationary, which comprises motive means having a rotatable driving element, means for mounting said motive means adjacent said shaft in a condition stationary with respect to said shaft, a cylindrical housing encircling said shaft adjacent said area to be resurfaced and having bearing means completely encircling said shaft and disposed adjacent and in contact with said shaft for rotatably supporting said housing about the axis of said shaft, a drive coupling between said element and said housing, a machining tool carried by and rotatable bodily with said housing and operable toward and from said area of said shaft to engage and machine said area as the tool rotates, means carried by said housing for feeding said tool progressively in a direction parallel to the shaft axis during its rotation with said housing and along said area, and means engaging said housing to take the thrust of said tool in both directions parallel to the axis of said shaft.

3. The apparatus according to claim 2, wherein said means for feeding said tool is a feed-screw assembly.

4. Apparatus for resurfacing a selected axially extending portion of a shaft, which comprises a split, cylindrical shell surrounding said shaft and having a flange at at least one end thereof, total encircling means rotatably supporting said shell on said shaft and in contact with said shaft over its entire encirclement, driving means for rotating said shell at a selected speed around said shaft, a tubular guide bar mounted on said shell externally thereof and parallel with the axis of said shell, a tool holder slidable axially on said bar, means for restraining said tool from rotation on said bar, feed means for moving said tool holder axially of said bar, said shell having an opening inwardly of said tool holder to permit a tool carried by said holder to engage said shaft as said shell is rotated about said shaft, and thrust bearing means engaging said flange to position said shell axially of said shaft and hold it against displacement in either axial direction.

5. Apparatus according to claim 4, in which a ring gear is provided on the end of said shell opposite said flange and said driving means comprises a motor having a pinion engaging said ring gear and means for mounting said motor on said shaft.

6. Apparatus according to claim 5, in which said motor is a Variable speed air motor.

7. Apparatus for resurfacing a selected axially extending portion of a shaft while the shaft is stationary, which comprises a split cylindrical shell surrounding said shaft and having integral flanges at opposite ends thereof, bearing means in opposite end portions of said shell bearing directly on said shaft and completely encircling said shaft for accurately centering said shell relatively to said shaft, thrust bearing means engaging said flange at one end of said shell to restrain said shell against displacement in either axial direction, an annular driving member mounted on said flange at other end of the shell, driving means cooperating with said driving member to rotate said shell about said shaft at a selected speed, means for mounting said driving means on said shaft, a tool mounted on said shell for movement axially of said shell and radially inwardly into engagement with said work and feed means for moving said tool axially of said shell as said shell is rotated about said shaft.

8. Apparatus according to claim 7, in which said driving member comprises a ring gear and wherein said bearing means are split cylindrical rings.

9. Apparatus for resurfacing a selected axially extending portion of a shaft, which comprises a split cylindrical shell surrounding said shaft and having a radial flange at at least one end, bearing means completely encircling said shaft and rotatably supporting said shell for rotation on said shaft in accurately centered relationship thereto, driving means for rotating said shell at a selected speed, a tubular guide bar mounted on said shell externally thereof and parallel with the axis of said shell, said guide having a longitudinal slot therein, a rotatable feed screw extending lengthwise of said slot, a tool holder closely surrounding said guide bar and axially slidable thereon, said tool holder having a portion extending into said slot to hold said tool holder against rotation on said bar and having a threaded surface engaging said screw, means for rotating said screw as said shell is rotated to move said tool holder axially along said guide bar and thrust bearing means cooperating with said flange to restrain said shell against axial movement in either direction.

10. Apparatus for resurfacing a selected portion of a shaft adjacent a stationary structure through which said shaft extends, which comprises a split cylindrical shell surrounding said shaft and having a radial flange at one end thereof, bearing means in opposite end portions of said shell encircling said shaft and rotatably engaging said shaft and accurately centering said shell on said shaft, annular thrust bearing means engaging opposite faces of said flange, means for securing said annular thrust bearing means to said stationary structure to hold said shell in accurate axial position relative to said shaft, a ring gear on the end of said shell opposite said flange, a driving motor having a pinion in driving engagement with said ring gear, means for mounting said motor on said shaft adjacent the end of said shell on which said ring gear is provided and means on said shell carrying a resurfacing tool adapted to engage and resurface said selected portion of the shaft as said shell is rotated about the shaft.

1l. An apparatus for resurfacing a peripherally extending area of a shaft while the shaft is stationary, which comprises motive means having a rotatable driving element, means for removably mounting said motive means adjacent said shaft in a condition Vstationary with respect to said shaft, a cylindrical housing selectively mountable encircling a portion of said shaft including said area to be resurfaced and adjacent bearing bands removable shoe means disposed in opposite end portions of said housing and in contact with said bearing bands of said shaft for rotatably supporting said housing about the axis of said shaft, a drive coupling between said element and said housing, a resurfacing tool carried by said housing intermediate its ends and rotatable bodily with said housing, said tool being operable toward and from said area of said shaft to engage and resurface said area as the housing and tool rotate, means carried by said housing for feeding said tool progressively in a direction parallel to the shaft axis during its rotation with said housing and along said area, means engaging said housing to take the thrust of said tool in both directions parallel to the axis of said shaft, and said shoe means comprising sets of removably and replaceable arcuate shoes configured to have an internal contour to adapt said housingfor use on different diameter shafts.

12. Apparatus for resurfacing a selected axially extending portion of a shaft, which comprises a split, cylindrical shell removably mounted selectively surrounding said shaft and having a flange at least at one end thereof, means rotatably and removably supporting said shell on said shaft, independent driving means mountable on said shaft for rotating said shell at a selected speed around said shaft, a tubular guide bar mounted on said shell externally thereof and parallel with the axis of said shell, a tool holder for holding a tool and disposed for traveling axially on said bar between the ends of said shell, means for restraining said tool holder from rotation on said bar, means for moving said tool holder axially of said bar, saidV shell having an opening inwardly of said tool holder to permit a tool carried by said holder to engage said shaft as said shell is rotated about said shaft, and thrust bearing means releasably engaging said flange to position said shell coaxially of said shaft and hold it against displacement in either axial direction.

13. Apparatus according to claim 12, in which a ring gear is provided on the end of said shell opposite said 4flange and said driving means comprises a motor having a pinion engaging said ring gear.

14. Apparatus according to claim 13, in which said motor is a variable speed air motor.

15. Apparatus for resurfacing a selected axially extending portion of a shaft while the shaft is stationary, which comprises a split cylindrical shell removably mounted surrounding said shaft and having integral flanges at opposite ends thereof, arcuate bearing shoes in opposite end portions of said shell bearing directly on said shaft for accurately centering said shell relatively to said shaft, thrust bearing means releasably engaging said flange at one end of said shell to .restrain said shell against displacement in either axial direction, an annular driving member mounted on said flange at the other end of the shell, driving means cooperating with said driving member to rotate said shell circumferentially about said shaft at a selected speed, means for removably mounting said driving means on said shaft, a tool mounted on said shell for movement axially of said shell between the ends of the shell and radially inwardly into engagement with said shaft, and feed means for progressively moving said tool axially of said shell as said shell is rotated about said shaft.

16. Apparatus for resurfacing a selected axially extending annular area of a shaft while said shaft is stationary, which comprises:

(a) a split cylindrical shell surrounding said shaft and having integral radial flanges at opposite ends thereof,

(b) arcuate bearing shoes in opposite end portions of said shell bearing direct-ly on said shaft for rotatably supporting said shell on said shaft in accurately centered relationship to said shaft,

(c) stationary thrust bearing means releasably engaging said flange at one end of said shell to restrain said shell against displacement in either axial direction,

(d) an annular gear mounted on said flange at the other end of the shell,

(e) a fluid motor having a driving pinion,

'fifi (f) means mounting said motor stationarily on said shaft with said pinion in driving relation to said gear whereby said shell is rotated on said shaft by said motor,

(g) guide bar means mounted on said shell externally thereof and extending parallel to the axis of said shell between said llanges,

(h) a tool holder movable axially on said guide bar means between said flanges,

(i) means for restraining said tool holder from rotation on said guide bar means,

(j) means for progressively moving said tool holder axially of said guide bar means,

(k) a tool carried by said tool holder in position to engage a portion of said shaft between said shoes, said shell having an opening inwardly of said tool holder to permit said tool to engage said shaft as said shell is rotated on said shaft and (l) means for moving said tool radially inwardly to remove a selected amount of material from said shaft as said shell is rotated.

References Cited in the le of this patent UNITED STATES PATENTS 1,417,621 Marsh May 30, 1922 2,201,664 Ferguson May 2l, 1940 2,553,570 Flynn May 22, 1951 2,869,411 Duprat .'an. 20, 1959 FOREIGN PATENTS 1,870 Great Britain Jan. 24, 1906 108,913 Australia July 13, 1938 

4. APPARATUS FOR RESURFACING A SELECTED AXIALLY EXTENDING PORTION OF A SHAFT, WHICH COMPRISES A SPLIT, CYLINDRICAL SHELL SURROUNDING SAID SHAFT AND HAVING A FLANGE AT AT LEAST ONE END THEREOF, TOTAL ENCIRCLING MEANS ROTATABLY SUPPORTING SAID SHELL ON SAID SHAFT AND IN CONTACT WITH SAID SHAFT OVER ITS ENTIRE ENCIRCLEMENT, DRIVING MEANS FOR ROTATING SAID SHELL AT A SELECTED SPEED AROUND SAID SHAFT, A TUBULAR GUIDE BAR MOUNTED ON SAID SHELL EXTERNALLY THEREOF AND PARALLEL WITH THE AXIS OF SAID SHELL, A TOOL HOLDER SLIDABLE AXIALLY ON SAID BAR, MEANS FOR RESTRAINGING SAID TOOL FROM ROTATION ON SAID BAR, FEED MEANS FOR MOVING SAID TOOL HOLDER AXIALLY OF SAID BAR, SAID SHELL HAVING AN OPENING INWARDLY OF SAID TOOL HOLDER TO PERMIT A TOOL CARRIED BY SAID HOLDER TO ENGAGE SAID SHAFT AS SAID SHELL IS ROTATED ABOUT SAID SHAFT, AND THRUST BEARING MEANS ENGAGING SAID FLANGE TO POSITION SAID SHELL AXIALLY OF SAID SHAFT AND HOLD IT AGAINST DISPLACEMENT IN EITHER AXIAL DIRECTION. 